Automatic adjusting method for proportion mode of centrifugal fan

Abstract

The invention discloses an automatic proportional mode adjusting method for a centrifugal fan. The method comprises the following steps that an intermediate pressure flow equation y1 = m1x + b1 is determined according to the current fan flow requirement, a < = y1 < = c, when y1 = a, x = X1, and when y1 = c, x = X2; determining a two-side proportion equation and a proportion value t1, a left side equation y2 = m2x + b2, a right side equation y3 = m3x + b3, a < = y2 < = c, a < = y3 < = c, when y2 = a, x = X3, when y2 = c, x = X4, when y3 = a, x = X5, and when y3 = c, x = X6; when the flow needs to be integrally changed during operation, a new proportion value t2 is determined, a new intermediate pressure flow equation y4 = m4x + b4 is obtained, y4 is larger than or equal to a and smaller than or equal to c, when y4 = a, x = X7, and when y4 = c, x = X8 is obtained; and the fan flow is controlled according to the new intermediate pressure flow equation, the rotating speed of the centrifugal fan can be flexibly adjusted according to actual process requirements, it is ensured that the fan is always kept in the optimal operation state, the air flow requirements of different process stages are met, energy consumption is reduced, and the operation efficiency and system stability of the fan are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fans, and in particular to a method for automatically adjusting a proportional mode of a centrifugal fan. Background Art

[0002] The more common processes for sewage treatment are AO process, A20 process, MBR process, SBR process, CASS process, etc. When there is a decanting stage in the process, the required gas volume is smaller than normal. When the decanting is completed and the water is refilled, the required gas volume needs to slowly increase until it reaches the normal operating gas volume. At this time, the water level also reaches the normal water level. The oxygen demand will change during the operation of the entire process, and the fan operation system needs to be adjusted to adapt to the gas volume required at each stage, but how to make a quick and safe adjustment method. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a method for automatic adjustment of the proportional mode of a centrifugal fan, which can flexibly adjust the speed of the centrifugal fan according to actual process requirements, ensure that the fan always remains in the best operating state, meet the gas volume requirements of different process stages, reduce energy consumption and improve the operating efficiency of the fan and system stability.

[0004] Technical solution:

[0005] A centrifugal fan proportional mode automatic adjustment method comprises the following steps:

[0006] 1) According to the current fan flow requirement, determine the intermediate pressure flow equation y1=m1x+b1, a≤y1≤c, when y1=a, x=X1, when y1=c, x=X2;

[0007] 2) Determine the proportional equations on both sides and the proportional value t1, the left equation y2=m2x+b2, the right equation y3=m3x+b3, a≤y2≤c, a≤y3≤c, when y2=a, x=X3, when y2=c, x=X4, when y3=a, x=X5, when y3=c, x=X6;

[0008] 3) When the flow rate needs to change as a whole during operation, determine the new proportional value t2, and obtain the new intermediate pressure flow equation y4=m4x+b4, a≤y4≤c, when y4=a, x=X7, when y4=c, x=X8;

[0009] 4) Control the fan flow according to the new intermediate pressure flow equation.

[0010] During the operation of the fan, flow and pressure are closely related. The performance diagram of the fan is usually expressed as the relationship between flow and pressure. With the known flow demand, an intermediate pressure-flow equation can be calculated, which describes the pressure state under the current flow conditions. This step determines the basic pressure-flow relationship of the fan at a specific flow rate, providing benchmark data for subsequent adjustments. The intermediate equation y1=m1x+b1 is the starting point of the fan operation and provides an initial pressure value based on the current flow demand. Under different working conditions of the fan, the relationship between pressure and flow will be different. After determining the pressure-flow equation of the middle line, although it can be used to increase or decrease the speed according to the actual flow, when the overall flow demand changes, it will be simpler and safer to use the left and right boundary lines and proportional values ​​to adjust the flow.

[0011] Furthermore, step 2) selects to determine the proportional value according to the two-side proportional equation.

[0012] Furthermore, step 2) specifically includes: determining the proportional value t1 = (X4-X2) / (X6-X4) = (X3-X1) / (X5-X3) according to the two-side equations y2 = m2x + b2, y3 = m3x + b3 and the intermediate pressure flow equation y1 = m1x + b1.

[0013] Furthermore, data points close to the boundary of the performance graph are selected. The data points here can be set arbitrarily, but in order to maximize the adjustable area, data points as close to the boundary of the performance graph as possible are selected, and the proportional equation on both sides is calculated through the data points.

[0014] Furthermore, in step 2), the proportional equation of both sides is first determined according to the proportional value.

[0015] Furthermore, step 2) specifically includes: first selecting the relationship between the proportional equations on both sides t1=(m2-m1) / (m3-m2)=(b2-b1) / (b3-m2) according to the proportional value t1 and the intermediate pressure flow equation y1=m1x+b1, and then determining the proportional equations on both sides according to the relationship between the proportional equations on both sides and actual needs.

[0016] Furthermore, step 3) specifically includes: according to the two-side equations y2=m2x+b2 and y3=m3x+b3 and the new proportional value t2, the slope of the middle straight line is obtained as m4=(1-t2)m2+tm3, and the slope of the middle straight line as b4=(1-t2)b2+tb3, thereby obtaining the new intermediate pressure flow equation y4=m4x+b4.

[0017] Beneficial effect: Through the proportional mode automatic adjustment method of the present invention, the speed of the centrifugal fan can be flexibly adjusted according to the actual process requirements, ensuring that the fan always maintains the best operating state, meeting the gas volume requirements of different process stages, reducing energy consumption and improving the operating efficiency of the fan and system stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the principle diagram of the automatic adjustment process of the present invention;

[0019] Figure 2 is a performance diagram of the centrifugal fan of the present invention;

[0020] Figure 3 It is a schematic diagram of the proportional mode operation area of ​​the centrifugal fan of the present invention. DETAILED DESCRIPTION

[0021] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] like Figure 1 As shown, a centrifugal fan proportional mode automatic adjustment method comprises the following steps:

[0024] 1) According to the current fan flow requirement, determine the intermediate pressure flow equation y1=m1x+b1, a≤y1≤c, when y1=a, x=X1, when y1=c, x=X2;

[0025] 2) Determine the proportional equations on both sides and the proportional value t1, the left equation y2=m2x+b2, the right equation y3=m3x+b3, a≤y2≤c, a≤y3≤c, when y2=a, x=X3, when y2=c, x=X4, when y3=a, x=X5, when y3=c, x=X6;

[0026] 3) When the flow rate needs to change as a whole during operation, determine the new proportional value t2, and obtain the new intermediate pressure flow equation y4=m4x+b4, a≤y4≤c, when y4=a, x=X7, when y4=c, x=X8;

[0027] 4) Control the fan flow according to the new intermediate pressure flow equation.

[0028] During the operation of the fan, flow and pressure are closely related. The performance diagram of the fan is usually expressed as the relationship between flow and pressure. With the known flow demand, an intermediate pressure-flow equation can be calculated, which describes the pressure state under the current flow conditions. This step determines the basic pressure-flow relationship of the fan at a specific flow rate, providing benchmark data for subsequent adjustments. The intermediate equation y1=m1x+b1 is the starting point of the fan operation and provides an initial pressure value based on the current flow demand. Under different working conditions of the fan, the relationship between pressure and flow will be different. After determining the pressure-flow equation of the middle line, although increasing or decreasing the speed according to the actual flow rate can meet the use, when the overall flow demand changes, it will be simpler and safer to use the left and right boundary lines and the proportional value when adjusting the flow. The middle line here assumes the scope of use of customer needs first, which needs to be determined first. The value of X and the order of the left and right lines can be interchanged.

[0029] In this embodiment, step 2) selects to determine the proportional value according to the two-side proportional equation.

[0030] In this embodiment, step 2) specifically includes: determining the proportional value t1 = (X4-X2) / (X6-X4) = (X3-X1) / (X5-X3) based on the two-side equations y2 = m2x + b2, y3 = m3x + b3 and the intermediate pressure flow equation y1 = m1x + b1.

[0031] In this embodiment, data points close to the boundary of the performance graph are selected.

[0032] Furthermore, in step 2), the proportional equation of both sides is first determined according to the proportional value.

[0033] Furthermore, step 2) specifically includes: first selecting the relationship between the proportional equations on both sides t1=(m2-m1) / (m3-m2)=(b2-b1) / (b3-m2) according to the proportional value t1 and the intermediate pressure flow equation y1=m1x+b1, and then determining the proportional equations on both sides according to the relationship between the proportional equations on both sides and actual needs.

[0034] Furthermore, step 3) specifically includes: according to the two-side equations y2=m2x+b2 and y3=m3x+b3 and the new proportional value t2, the slope of the middle straight line is obtained as m4=(1-t2)m2+tm3, and the slope of the middle straight line as b4=(1-t2)b2+tb3, thereby obtaining the new intermediate pressure flow equation y4=m4x+b4.

[0035] To make the technical solution of the present invention clearer, specifically, in this embodiment, Figure 2 As shown, the rated pressure of the fan in this example is 60KPA and the rated power is 85KW. Figure 2The vertical axis is pressure (mmaq), and the horizontal axis is flow rate (m 3 / min), the left value and the long solid curve are the speed value and the speed line, and the right value and the downward sloping dotted line are the power value and the power line.

[0036] Corresponding to step 1), assuming that the pressure and air volume used during normal explosion are 5500mmaq-55m 3 / min, the pressure drops to 3000mmaq-35m 3 / min. Draw the operating area, such as Figure 2 As shown. According to the data 5500mmaq-55m 3 / min~3000mmaq-35m 3 / min performance requirements are drawn Figure 2 In the figure, the middle line segment of the pressure-flow equation.

[0037] Corresponding to step 2), this embodiment calculates according to the ratio t1=50%, and according to the demand, the left and right line segments are 5500mmaq-39m 3 / min~3000mmaq-30m 3 / min on the left; 5500mmaq-71m 3 / min~3000mmaq-40m 3 / min, such as Figure 3 The data points selected by the two line segments here correspond to the previous ratio value t1 = 50%. 3 / min~3000mmaq-35m 3 When the / min and proportion value 50% change, just change the corresponding data points above.

[0038] The left and right straight line equations are obtained by using the principle that two points form a straight line. The left equation is y2=m2x+b2, and the right equation is y3=m3x+b3. Under the current operating pressure, the flow rates of the left and right line segments can be obtained by using the left and right equations. The difference between the flow rate obtained by the right equation and the flow rate obtained by the left equation is multiplied by 0.5 and then added to the flow rate obtained by the left equation, which is 5500mmaq-55m 3 / min~3000mmaq-35m 3 / min is the flow rate that this line segment needs to achieve under the current pressure.

[0039] The left and right lines are used to assist in adjustment. For example, when the flow rate is proportionally larger than the previous demand within a period of time, you can reset the two points and re-determine the equation. In order to avoid setting parameter errors and facilitate adjustment, the left boundary line is 0% and the right boundary line is 100%. Similarly, the 0% and 100% here can be freely selected. For example, according to Figure 2 The left boundary data is 5500mmaq-39m 3 / min-3000mmaq-30m 3 / min; in fact, it can also be set to 5500mmaq-45m 3 / min-3000mmaq-34m 3 / min. The set point here can be set arbitrarily, but in order to maximize the adjustable area, it is better to select data points as close to the boundary of the performance graph as possible.

[0040] The ratio value needs to be considered in conjunction with the left and right boundary lines. When the middle line and the left and right boundaries are determined, the ratio value is obtained, that is, the ratio of the flow of the middle line to the left and right boundaries under the same pressure, ((middle line flow value - left boundary flow value) / (right boundary flow value - left boundary flow value)) is equal to the ratio value, which is affected by the middle line and the left and right boundary lines. When the flow does not need to change as a whole during operation, the left and right boundary lines are not needed, and even the ratio value is not needed. However, when the overall flow demand changes, it will be simpler and safer to use the left and right boundary lines and the ratio value to adjust the flow.

[0041] Corresponding to step 3), when the flow rate needs to be increased within a period of time, it is assumed to be adjusted to 5500mmaq-60.5m 3 / min~3000mmaq-38.5m 3 / min.

[0042] Then just adjust the value of t from the previous 50% (t1) to 67.2% (t2); the data of the left and right lines are: 5500mmaq-39m 3 / min~3000mmaq-30m 3 / min; 5500mmaq-71m 3 / min~3000mmaq-40m 3 / min; (55-39) / (71-39)=50%; (60.5-39) / (71-39)=67.2%.

[0043] The adjustment method of this method avoids the situation that the output air volume of the fan cannot be output according to the process requirements due to pressure changes. When the process requires the air volume to increase within a certain period of time, the output air volume required by the process of the entire process can be automatically corrected.

[0044] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A centrifugal fan proportional mode automatic adjustment method, characterized in that: The following steps are involved: 5) Determine the intermediate pressure flow equation y1=m1x+b1 according to the current fan flow requirement, a≤y1≤c, when y1=a, x=X1, when y1=c, x=X2; 6) Determine the proportional equations on both sides and the proportional value t1, the left equation y2=m2x+b2, the right equation y3=m3x+b3, a≤y2≤c, a≤y3≤c, when y2=a, x=X3, when y2=c, x=X4, when y3=a, x=X5, when y3=c, x=X6; 7) When the flow rate needs to change as a whole during operation, determine the new proportional value t2, and obtain the new intermediate pressure flow equation y4=m4x+b4, a≤y4≤c, when y4=a, x=X7, when y4=c, x=X8; 8) Control the fan flow according to the new intermediate pressure flow equation.

2. The method for automatically adjusting the proportional mode of a centrifugal fan according to claim 1, characterized in that: Step 2) Select to determine the proportional value based on the two-sided proportional equation.

3. The method for automatically adjusting the proportional mode of a centrifugal fan according to claim 2, characterized in that: Step 2) specifically includes: determining the proportional value t1 = (X4-X2) / (X6-X4) = (X3-X1) / (X5-X3) according to the two-side equations y2 = m2x + b2, y3 = m3x + b3 and the intermediate pressure flow equation y1 = m1x + b1.

4. The method for automatically adjusting the proportional mode of a centrifugal fan according to claim 2, characterized in that: Pick data points that are close to the border of the performance graph.

5. The method for automatically adjusting the proportional mode of a centrifugal fan according to claim 1, characterized in that: Step 2) First select the proportional equation for both sides based on the proportional value.

6. A centrifugal fan proportional mode automatic adjustment method according to claim 5, characterized in that: Step 2) specifically includes: firstly, according to the proportional value t1 and the intermediate pressure flow equation y1=m1x+b1, determine the relationship between the proportional equations on both sides t1=(m2-m1) / (m3-m2)=(b2-b1) / (b3-m2), and then determine the proportional equations on both sides according to the relationship between the proportional equations on both sides and actual needs.

7. The method for automatically adjusting the proportional mode of a centrifugal fan according to claim 1, characterized in that: Step 3) specifically includes: according to the two-side equations y2=m2x+b2 and y3=m3x+b3 and the new proportional value t2, the slope of the middle straight line m4=(1-t2)m2+tm3 and the slope of the middle straight line b4=(1-t2)b2+tb3 are obtained, and then the new intermediate pressure flow equation y4=m4x+b4 is obtained.

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